Magnetically actuated devices may be designed for a variety of purposes such as, e.g., electrical switching, position sensing, synchronization, flow measurement, and stirring. Particularly important among such devices are so-called reed switches as described, e.g., in the book by L. R. Moskowitz, Permanent Magnet Design and Application Handbook, Cahners Books, 1976, pp. 211-220, in U.S. Pat. No. 3,624,568, issued Nov. 30, 1971 to K. M. Olsen et al., and in the paper by M. R. Pinnel, "Magnetic Materials for Dry Reed Contacts", IEEE Trans. Mag., Vol. MAG-12, No. 6, November 1976, pp. 789-794. Reed switches comprise flexible metallic reeds which are made of a material having semihard magnetic properties as characterized by an essentially square B-H hysteresis loop and high remanent induction B.sub.r ; during operation reeds bend elastically so as to make or break electrical contact in response to changes in a magnetic field.
Among established alloys having semihard magnetic properties are Co-Fe-V alloys known as Vicalloy and Remendur, Co-Fe-Nb alloys known as Nibcolloy, and Co-Fe-Ni-Al-Ti alloys known as Vacozet. These alloys possess adequate magnetic properties; however, they contain substantial amounts of cobalt whose rising cost in world markets causes concern. Moreover, high cobalt alloys tend to be brittle, i.e., to lack sufficient cold formability for shaping, e.g., by cold drawing, rolling, bending, or flattening.
Relevant with respect to the invention are the book by M. Hansen, Constitution of Binary Alloys, 2nd edition, McGraw-Hill, 1958, pp. 664-667; the book by R. M. Bozorth, Ferromagnetism, Van Nostrand, 1951, pp. 234-236 and pp. 418-419; the paper by M. J. Roberts, "Effect of Transformation Substructure on the Strength and Toughness of Fe-Mn Alloys", Met. Trans., Vol. 1, December 1970, pp. 3287-3294, the paper by F. M. Walters, Jr., "Transformations and Heterogeneity in the Binary Alloys of Iron and Manganese", Trans. American Soc. for Steel Treating, Vol. 21, No. 10, 1933, pp. 1002-1015, and the paper by G. M. Fedash, "Study of Coercivity of Cold-Worked and Annealed Iron Alloys", The Physics of Metals and Metallography, Vol. 4, No. 2, 1957, pp. 50-55. These references discuss phase transformations, mechanical properties, and coercivity of iron-rich Fe-Mn alloys. Semihard magnetic properties of Fe-Mn ternary and quaternary alloys are disclosed by W. Jellinghaus, "Kaltverformter Manganstahl als neuer Magnetwerkstoff", Archiv fur das Eisenhuttenwesen, Vol. 15, No. 2, August 1941, pp. 99-102, by H. Kaneko et al., "Cold Worked Fe-Mn Semihard Magnet Alloy", Journal of the Japanese Institute of Metals, Vol. 34, No. 4, 1970, pp. 441-445, and by K. Ogawa, "Semihard Magnetic Material of the Fe-Cu-Mn System", J. App. Phys., Vol. 44, No. 4, April 1973, pp. 1810-1812.